In many merchandising machines known in the prior art an article which has been dispensed by one of a plurality of dispensing units in response, for example, to the deposit of money in the machine and to the actuation of a selecting mechanism drops into a delivery box located behind an opening in the machine cabinet. This access opening normally is closed by the delivery box door, which is adapted to be opened in some instances by pushing on the door actuator to gain access to the interior of the box. It also has been suggested in the prior art that means responsive to opening of the door be provided for preventing access to the merchandise carrying units of the machine by, for example, the insertion of a wire through the access opening and around the door to the merchandise carrying unit which usually are located above the door. In general, these mechanisms for preventing access to the merchandise carrying units are complicated and expensive. In many merchandising machines, the door is not locked during the inactive condition of the machine and can be held open and the machine can be operated with the door open. The danger exits that the mechanism may become jammed if an article is delivered by a dispensing unit while the door is thus held open.